A Scenario Driven Hazard Analysis of the Operation of Escalators

Abstract

An escalator constitutes a system utilizing both mechanical and electrical devices. The interfaces between these devices along with the interactions of various environmental conditions and user behaviors further establish that an escalator system is not simple, but rather, very complex in nature. Therefore, it is imperative that the potential risks associated with such a complex system are recognized and thoroughly evaluated.

Introduction

According to the U.S. Elevator World Inc.’s Vertical Transportation Industry Profile, roughly 30,000 escalators are used to move people up and down every day. This equates to approximately 250 million escalator rides per day. The unknowing passenger would like to think that he or she is safe on such a widely used means of transportation. However, information released by the Consumer Product Safety Commission revealed that escalator incidents resulted in 16,000 injuries in 1997, 7,300 of which required hospitalization. More notably, twenty fatalities were recorded from 1997 to 2003 on escalator systems – approximately three deaths per year. These statistics ascertain the need for a comprehensive system safety analysis which addresses all potential system risks.

Comprehensive Analysis

The aim of this report is to utilize a three pronged attack towards developing a comprehensive scenario-driven hazard analysis of escalator operation. Specifically, it employs three analytical techniques – Link Analysis, Maintenance, and the combination of Behavior Sampling and Human Interface Analysis – to cover potential scenarios which ultimately result in hazards. This particular combination of analyses was chosen for the purpose of exploiting the maximum coverage of accident scenarios.

While there is some published information on the dangers associated with escalators as well as statistics reporting on the number of various types of incidents, there is no published data on the true complexity of the system...